Liquid filter assembly

ABSTRACT

A liquid filter assembly including a first liquid filter element adapted to filter particles larger than a first size; a second different liquid filter element adapted to filter particles larger than a second size; a housing having the first and second liquid filter elements therein. The second size is smaller than the first size. The housing forms a first liquid flow path having the first liquid filter element therein, and a second liquid flow path having the second liquid filter element therein. The second filter element comprises a formed porous polymer member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) on U.S.Provisional Patent Application No. 60/602,572 filed Aug. 18, 2004 andU.S. Provisional Patent Application No. 60/611,966 filed Sep. 21, 2004which are hereby incorporated by reference in their entireties, and is acontinuation-in-part patent application of application Ser. No.10/424,448 filed Apr. 28, 2003, now U.S. Pat. No. 7,048,848, which is acontinuation-in-part patent application of application Ser. No.09/812,977 filed Mar. 20, 2001, now U.S. Pat. No. 6,605,215.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to filtration systems and methods and,more particularly, to a filter assembly intended to remove impuritiesfrom a liquid, such as a lubricant, and, more specifically still, to ahybrid spin-on oil filter assembly for use with an internal combustionengine which provides a dual-stage filtering action that includes afirst oil filter section in combination or in parallel with a secondbypass oil filter section.

2. Brief Description of Prior Developments

U.S. Pat. Nos. 4,761,232 and 6,030,558, which are hereby incorporated byreference in their entireties, disclose porous plastic or polymermembers. Conventional internal combustion engines used in automobilesand similar vehicles include a spin-on oil filter assembly for cleaningthe motor oil. However, due to the fact that the conventional oil filterassembly only effectively removes particles of size 10 microns andlarger, after some period of time smaller particles build up in theengine oil and require that the engine oil be replaced. Typical engineoil, and oil filter, replacement schedules are every 3,000 miles orthree months, whichever occurs first.

It is known in certain types of vehicles, such as large trucks, to usean auxiliary bypass filter for additional filtering. A typical bypassfilter retrofits to the truck engine where it diverts oil through afiner auxiliary filter element at a slower flow rate than the normal oilfilter (e.g. 2.5 gallons per minute or less versus about 20 to 40gallons per minute). Passing the engine oil through the auxiliary filterelement aids in filtering out particles smaller than about 40 microns insize, thereby improving engine oil life as well as the life of theengine. Reference in this regard can be had to, for example, U.S. Pat.No. 5,552,065, Meddock et al.

However, this type of filtering arrangement is not typically suitablefor use with automobiles and similar types of vehicles. A first issuerelates to the difficulty in retrofitting a bypass oil filter assemblyto the engine. In many cases there may simply not be room to mount thebypass oil filter assembly. A second issue relates to cost, as the useof the bypass oil filter assembly is inherently more costly than the useof only the conventional type of oil filter assembly.

As can be appreciated, there is a significant body of prior art that hasbeen built up over the decades relating to oil filters and relatedtechniques for internal combustion engines. Representative of this priorart are the following U.S. Patents.

In U.S. Pat. No. 3,986,960, Wire et al., describe a fluid filtercontaining a tubular canister having a contaminated fluid inlet and afiltered fluid outlet. The filter includes a solid tube forming avertical central conduit within the canister and a plurality of axiallyspace-apart containers mounted serially along the tube. Filteringmaterial is located in the canisters. Ports in the tube communicate withchambers formed between the filter element and the bottom of thecontainer. A seal is effected between the outlet of the canister and thetube, while fluid communication is provided between the inlet and theopen tops of the containers such that fluid flow occurring between theinlet and the outlet takes place through the filter elements.

In U.S. Pat. No. 4,048,071, Yamada et al. describe a liquid filteringdevice where the peripheral surface of a coil of a filter web woundabout a hollow shaft is covered by a liquid-impervious flexible coating,and the outer periphery of a first end of the coil is secured to asupporting disc so that when liquid to be filtered is caused to passthrough the coil in the axial direction of the coil, the convolutions ofthe coil near a second end expand radially outwardly to trapcontaminants in the spiral gap. Purified liquid collected at the firstend of the coil is discharged through the hollow shaft. The filter unitis constructed such that a number of unites can be connected in series.

In U.S. Pat. No. 4,738,776 Brown describes a lubricant filter assemblyfor an internal combustion engine that includes a head member removablymounted on a base member. The head member includes a sleeve-like housingopen at one end and having first and second filter units fixedly mountedtherein. The outer peripheries of the filter units coact with theinterior surface of the housing to form a common inlet passage. One ofthe filter units is provided with an interior first outlet passage whichcommunicates with a first passage formation formed in the base member.The first passage formation communicates with a first lubricatingcircuit of the engine. The second filter unit is provided with aninterior second outlet passage which communicates with a second passageformation formed in the base member. The second passage formationcommunicates with a second lubricating circuit of the engine. Sealsections are carried by the head member. One seal section effects asealing engagement between the base member and a portion of the housingdefining the open end. A second seal section is disposed within thehousing and prevents direct communication between the inlet passage andthe first outlet passage. A third seal section is disposed within thehousing and prevents communication between the first and second outletpassages. The sealing engagement effected by the third seal section isenhanced upon the flow pressure within the interior first outlet passagebeing increased.

In U.S. Pat. No. 5,178,753 Trabold describes an oil filter for internalcombustion engines that is used in a secondary oil circuit in additionto a conventional oil filter. The oil filter includes a filter housingin which a filter element consists of a roll of absorbent paper that iswound about a rod. The oil filter is configured as a set of elementsthat comprises body sections and caps, and a rod with the rolled filterelement. The volume of the oil filter can be matched to a particularapplication by connecting a plurality of body sections with anappropriate number of rods.

In U.S. Pat. No. 5,556,543 Trabold describes an oil filter for internalcombustion engines. The oil filter includes a filter housing and afilter packing made of a porous deformable material, e.g., a roll ofabsorbent paper. To prevent the filter packing from being deformed andthereby preventing a smooth flow through the filter packing, stabilizingelements, e.g., stabilizing bars, are provided for fixing the form andposition of the filter packing within the filter housing.

A long-felt and unfulfilled need exists to provide an oil filterassembly for an internal combustion engine that provides, within aconventionally-sized oil filter container, a conventional oil filter anda bypass oil filter capable of entrapping and, thus, removing smallerparticles from the oil than the conventional oil filter.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a liquid filter assemblyis provided comprising a first liquid filter element adapted to filterparticles larger than a first size; a second different liquid filterelement adapted to filter particles larger than a second size, thesecond size being smaller than the first size; and a housing having thefirst and second liquid filter elements therein. The housing forms afirst liquid flow path having the first liquid filter element therein,and a second liquid flow path having the second liquid filter elementtherein. The second filter element comprises a formed porous polymermember, or alternatively a carbon polymer combination.

In accordance with another aspect of the invention, a liquid filterassembly is provided comprising a first liquid filter element adapted tofilter particles larger than a first size; a second different liquidfilter element located at least partially above the first filter elementand adapted to filter particles larger than a second size, the secondsize being smaller than the first size; and a housing having the firstand second liquid filter elements therein. The housing forms a firstliquid flow path having the first liquid filter element therein, and asecond liquid flow path having the second liquid filter element therein.The second filter element comprises a molded porous member comprising apolymer material. Alternatively the member could be die cast and latercut or stamped.

In accordance with another aspect of the invention, a liquid filterassembly is provided comprising a first liquid filter element adapted tofilter particles larger than a first size; a second different liquidfilter element adapted to filter particles larger than a second size,the second size being smaller than the first size; and a housing havingthe first and second liquid filter elements therein. The housing forms afirst liquid flow path having the first liquid filter element therein,and a second liquid flow path having the second liquid filter elementtherein. The second filter element comprises an extruded porous membercomprising a polymer material.

In accordance with one method of the invention, a method ofmanufacturing a liquid filter assembly is provided comprising providinga first filter element having a general ring shape; providing a secondfilter element, the second filter element comprising a formed porouspolymer member; connecting the second filter element to the first filterelement; and locating the first filter element and the second filterelement in a housing, wherein a first liquid flow path is provided inthe housing through the first filter element and a second liquid flowpath is provided in the housing through the second filter element, andwherein the first and second flow paths merge in a central area insidethe general ring shape of the first filter element.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the invention are explainedin the following description, taken in connection with the accompanyingdrawings, wherein:

FIG. 1 is diagram depicting the oil flow paths and typical pressures ofthe hybrid oil filter assembly in accordance with the teachings of thisinvention;

FIG. 2 is a cross-sectional view of one presently preferred embodimentof the hybrid oil filter assembly;

FIG. 2A is a simplified cross-sectional view of the embodiment of FIG. 2with the internal filtering material removed so as to more clearly showthe various inner volumes of the hybrid oil filter assembly;

FIG. 2B is a cross-sectional view of another presently preferredembodiment of the hybrid oil filter assembly;

FIG. 3 is an elevational view of a first micro-filter element insert;

FIG. 4 is a bottom view (looking from the motor) of the normal filterelement and the main inlet plate;

FIG. 5 is a bottom view showing a bypass valve in position;

FIG. 6 is a bottom view showing in greater detail the oil inlet to thenormal filter and the oil inlet to the micro-filter, including thebypass valve;

FIG. 7 is a top view of an oil holding valve or backflow valve and thesurrounding inlet plate to the micro-filter insert;

FIG. 8 is a top view of the oil holding valve and the surrounding inletplate to the micro-filter insert, as well as the bypass valve positionedover the oil holding valve;

FIG. 9 is a top view depicting the normal oil filter element thatcontains an orifice providing fluid communication between the highpressure micro-filtering portion and the lower pressure normal filteringportion;

FIG. 10 shows a back pressure valve and seal between the normal filter,the inside of a micro-filter tube and an upper outlet/inlet plate;

FIG. 11 is a top view of the outer micro-filter element;

FIG. 12 is a top view of the outer micro-filter element having the upperoutlet/inlet plate in position;

FIG. 13 is a schematic cross sectional view of an alternate embodimentof the filter assembly incorporating features of the invention;

FIG. 14 is a top plan view of the flutter valve used in the filterassembly shown in FIG. 13;

FIG. 15 is an enlarged partial cross sectional view of the filterassembly shown in FIG. 13 with the flutter valve moved to a first closedposition;

FIG. 16 is an enlarged partial cross sectional view as in FIG. 15 withthe flutter valve moved to a second closed position; and

FIG. 17 is a schematic cross sectional view of another alternateembodiment of the filter assembly of the invention.

FIG. 18 is a cut-away side view of an alternate embodiment of a filterassembly incorporating features of the invention;

FIG. 19 is a partial cross sectional view of the filter assembly shownin FIG. 18;

FIG. 20 is a partial cross sectional view of the filter assembly shownin FIG. 18;

FIG. 21 is an exploded perspective view of three of the components ofthe filter assembly shown in FIG. 18;

FIG. 22 is an exploded perspective view of the components shown in FIG.21 showing the flutter valve member mounted on the cover plate;

FIG. 23 is an exploded perspective view of the components shown in FIG.21 showing the micro filter member mounted on the cover plate;

FIG. 24 is a perspective view of the micro filter member shown in FIG.18;

FIG. 25 is a top plan view of the micro filter member shown in FIG. 24;

FIG. 26 is a cross sectional view of the micro filter member shown inFIG. 25 taken along line 26-26;

FIG. 27 is a cross sectional view of the micro filter member shown inFIG. 25 taken along line 27-27;

FIG. 28 is a partial cross sectional view of an alternate embodiment ofa filter assembly;

FIG. 29 is a perspective view showing the filter assembly of FIG. 28without the spring or outer housing;

FIG. 30 is a top plan view of the plate located above the flutter valveshown in FIG. 28;

FIG. 31 is a perspective view of the disk shaped micro-filter elementshown in FIG. 28;

FIG. 32 is a perspective view of the spring shown in FIG. 28;

FIG. 33 is a top plan view of the spring shown in FIG. 32;

FIG. 34 is a perspective view of an alternate embodiment of theinvention;

FIG. 35 is a perspective view of the filter assembly shown in FIG. 34with the outer housing removed;

FIG. 36 is a perspective view of the filter assembly as shown in FIG. 35with the outer micro-filter element removed;

FIG. 37 is a perspective view of the outer micro-filter element shown inFIG. 35;

FIG. 38 is a perspective view of the outer micro-filter element shown inFIG. 37 taken from an opposite side;

FIG. 39 is a partial cross sectional view of the filter assembly shownin FIG. 34;

FIGS. 40-42 are views of oil filters and cut away sections of housingsmembers used in European style cars which could be adapted to includefeatures of the invention;

FIG. 43 is a partial cross sectional view of another alternateembodiment of the invention;

FIG. 44 is a diagram illustrating another alternate embodiment of theinvention;

FIG. 45 is a diagram illustrating another alternate embodiment of theinvention;

FIG. 46 is a perspective view of the holder shown in the assembly ofFIG. 45;

FIG. 47 is a cross sectional view of the holder shown in FIG. 46;

FIG. 48 is a partial cut-away view of another alternate embodiment ofthe invention;

FIG. 49 is a partial perspective view of components of the assemblyshown in FIG. 48;

FIG. 50 is a partial cross sectional view of another alternateembodiment of the invention;

FIG. 51 is a partial perspective view of components of the assemblyshown in FIG. 50;

FIG. 52 is a partial perspective view of components of the assemblyshown in FIG. 51 with the spacer plug removed for illustration purposesonly;

FIG. 53 is an exploded perspective view of portions of another alternateembodiment of the present invention;

FIG. 54 is a perspective view of a sheet of filtering material used toform the second filter element shown in FIG. 53;

FIG. 55 is a perspective view of an alternate embodiment of the secondfilter element shown in FIG. 55; and

FIG. 56 is an exploded perspective view of portions of another alternateembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

By way of introduction, a hybrid oil filter assembly (HOFA) integratestwo filter systems into one spin-on filter housing, and may be used toreplace the conventional spin-on oil filter assembly for internalcombustion engines found in automobiles, vans, buses, trucks, heavymachine equipment, other internal combustion motor applications andhydraulic systems.

The HOFA can be mounted exactly the same as a normal, conventionalspin-on oil filter. The HOFA can be implemented using the same formfactors, sizes and threads as every other currently available spin-onfilter.

A significant difference between the HOFA design and the conventionalspin-on motor oil filter is an ability to filter the engine oilmicro-fine clean. In practice, the filtered motor oil can become asclean or cleaner than new, unused motor oil. The cleaning processprovides an ability to remove particles of size about one micron orgreater. The micro-cleaned motor oil protects the movable engine partsand thus prolongs the active engine life. Furthermore, the normal oilchange interval can be prolonged to, as an example, 15,000 miles orgreater.

Referring to FIG. 1, motor oil (MO) arrives from the motor oil pump ofthe engine and passes through holes in the bottom of the filter housinginto the HOFA (Point A). Most of the oil enters a first oil flow pathcontaining a first filter chamber (FFC), while a significantly smallerportion of the oil enters a second oil flow path containing a secondfilter chamber (SFC). The first oil filter chamber is substantiallyfilled with a first (conventional) filter media, such as pleated paper,and is filtered in a conventional manner. By example, the first filterchamber removes particles down to a size of about 10 microns. The secondfilter chamber is substantially filled with a second filter media, suchas rolled cellulose or paper, or glass wool, or plastic, or cotton, ormixtures of these and other filter materials, and is filtered(micro-filtered) so as to remove particles that are smaller in size thanthe particles removed in the first filter chamber. For example, theparticles removed in the second filter chamber may be as small as aboutone micron. The oil pressure at the outlet of the second filter chamber(designated C) is about 0.2% to about 0.8% less than the inlet pressureof x psi at point A. The oil pressure at the outlet of the first filterchamber (designated B) is about 2% to about 6% less than the inletpressure of x psi at point A. Since the filtered oil from the secondfilter chamber is injected under significant pressure into the firstfilter chamber, the interior volume of the first filter chamber alsoserves as a mixing zone wherein turbulent mixing occurs between thefiltered oil in the first filter chamber (FFC) and the micro-filteredoil injected from the second filter chamber (SFC). Micro-filtered oil inthe context of this invention includes oil that has been subjected to afiltering or cleaning operation wherein particles of a smaller size(e.g., down to about one micrometer) are retained than are retained inthe primary or conventional oil filter element (e.g., about 10micrometers).

FIG. 1 also shows the relationships between the inlet and outlet surfaceareas, and the relationships between the inlet and outlet pressures.

Referring to FIGS. 2 and 2A, motor oil 2 arriving with high pressurefrom the engine's oil pump passes through holes 32 in the bottom of thefilter housing. Oil fills all of the spaces 31 beneath and above theholes 32 before entering the filter housing 11 and encountering the twotypes of filter media.

One filter media is a filter element 30 which forms part of the normalor conventional filter. The filter element 30 may be a conventionalpleated paper type of filter material. Filter element 30 rests in acollar 33 supported by an assembly 14 that includes a threaded insert 13for engaging in a conventional manner threads that protrude from themotor housing. An oil holding valve 7 may be provided to limit oilspillage during filter spin-off.

A second filter media includes a first filter package embodied, in apreferred but not limiting embodiment, as a first micro-filter paperelement or insert 21 that is positioned circumferentially about thefirst filter element 30, and is separated therefrom by a tube 12. Thesecond filter media further may also include a second filter packageembodied, in a preferred but not limiting embodiment, as a secondmicro-filter paper element or insert 22 positioned over the top of thenormal filter element 30. In this case the tube 12 is longer than thefilter element 30 and separates the two micro-filter elements or inserts21, 22. Fluid communication between inserts 21 and 22 is made through anopen space 25 at the top of the filter housing 11, and through a topoutlet/inlet plate 23 having a plurality of holes 24. A spacer element26 is placed between the top surface of the end of the filter housing 11and the top plate 23 for urging the plate 23 against the top surfaces ofthe filter inserts 21 and 22. A bottom filter plate 19 having holes 20is located beneath the second micro-filter element 22, above a backpressure valve 18, preferably made of silicone, which is disposed overthe housing from filter 30 to provide a seal between all other filtermediums and oil chambers. The back pressure valve/seal has a centrallylocated orifice 16. Micro-filtered oil flows through the orifice 16 intothe volume of the filter center 6A where it mixes with the oil filteredthrough the first filter media element 30.

In operation, the greatest volume of incoming oil passes through holes32 to the side surfaces of the first filter media element 30, and thecleaned oil enters the space or void 6A at the center of the normalfilter element 30. From here the cleaned oil flows to the bearings andother parts of the engine.

A smaller volume of oil passes through holes 10 of a main inlet plate 9(see also FIGS. 4, 6, 7, 8), with the same pressure as the oil thatpasses into the filter element 30, and in through the filter elements 21and 22. The oil passes to the bottom surface of the micro-filter element21, through holes 24 of the upper outlet/inlet plate 23, through thelength of the second filter element 21, and arrives at the space 25 atthe top of the filter housing 11. The micro-fine filtered oil exits thespace 25, passes through additional holes 24 of the upper plate 23,passes through the second micro-filter paper element or insert 22,passes through holes 19 in plate 20 to the back pressure valve 18 andflows out through the orifice 15 of the top collar of the first filterinto the volume of the filter center region 6A. Once the micro-filteredoil arrives in the center region 6A of the normal filter portion themicro-fine filtered oil is mixed with the normally filtered oil. Themixed clean oil then flows to the engine through the conduit or outlet6.

The HOFA design employs a ratio of distribution of the oil and itspressure. More particularly, the HOFA operates based on the respectiveratios of the different pressures in different parts of the filter,resulting from different oil flow volumes.

The incoming oil 2 from the oil pump flows under pressure into thefilter housing 11 and passes through the two different filter media21/22 and 30. The pressure on all surfaces is equal, i.e., on thesurface of the normal filter element 30, on the surface of themicro-filter elements 21/22, and on the surface of the main inlet plate9. The oil passes relatively quickly through the pleats of the normalfilter element 30, but requires significantly more time to pass throughthe finer texture of the micro-filter elements 21/22. In a presentlypreferred embodiment the micro-filter elements 21 and 22 are tightlyrolled paper. The paper may be similar to that of bathroom tissue, butmay be manufactured for use in the HOFA. As a consequence about 95% ofthe incoming oil 2 passes through the normal filter element 30 and thecleaned oil flows out of conduit 6, at lower pressure, in the directionof the engine. Meanwhile, the same incoming pressure forces about 5% ofthe incoming oil 2 through the micro-filter element 21, through thespace 25 above the micro-filter element 21, through the upperoutlet/inlet plate 23, through micro-filter element 22, through the backpressure valve 18 and then through the outlet orifice 15. Thismicro-filtered oil mixes at open area 35 in the void 6A with thenormally filtered oil that passes through normal filter element 30, andthus joins the filtered oil passing through conduit 6 into the engine.Over time, all of the engine oil will pass through the micro-filterelements 21 and 22, and particles smaller than those trapped in thenormal filter element 30 are retained and filtered out of the oilstream, which is the desired result.

Based on the determined ratios between oil pressure, inflow volume,outflow volume, inlet surface and outlet surface in the micro-filterportion of the HOFA, the micro-filtered oil flows through the outletorifice 15 with a higher pressure than the pressure of the oil withinthe normal filter portion. Since the incoming oil volume cannot flow outat the same time through the orifice 15 at the top of the normal filterportion, consequently it forms a high oil pressure inside and around themicro-filter element inserts 21 and 22, which has typically the same oilpressure as the pressure in the line coming from the oil pump. Theresult is that the micro-filter element inserts 21 and 22 are constantlyimmersed or saturated in the oil, and the microscopic pores stay openand do not become compressed. The oil flow is thus normal in alldirections within the cellulose package (micro-filter element inserts 21and 22), and particles of size about one micron and greater are capturedand retained in the filter element inserts 21 and 22. In the presentlypreferred, but not limiting, embodiment the ratio between the inlet areaand the outlet area is about 400:1 at a pressure ratio of about 1:0.996.

Contrary to the micro-filter portion, the difference between the inletand outlet pressure of the normal full flow filter 30 is greater thanthe difference between the inlet pressure and the outlet pressure of themicro-fine filter elements 21 and 22. The resistance in the engine isless than at the outflow orifice in the micro-filter portion and theoutflow from the full flow filter. A reason for this behavior relates tothe resistance of the engine oil exiting the micro-filter portion atorifice 15. The ratio between inlet and outlet pressure of the full flowfilter 30 is about 1:0.96. The ratio between inlet and outlet pressureof the bypass filter 21, 22 is about 1:0.996. The flow through thebypass filter 21, 22 is slower than the flow through the full flowfilter 30, but because the size of the outlet from the bypass filter isso small, the pressure drop across the bypass filter 21, 22 is smallerthan the pressure drop across the full flow filter.

The above explanation of the different behaviors of the two filteringzones within the filter is an important consideration in explaining theoperation of the filter. The pressure differential causes the highpressure micro-fine cleaned oil to exit from the space 25 at the top ofthe filter housing 11, to be forced through the micro-filter media 22and through the orifice 15 in order to be mixed with the cleaned oilwithin the mixing volume 6A of the normal filter 30.

FIGS. 3-12, illustrating various components that were described above,provide further details of the placement of the components, theirshapes, and the construction of the HOFA.

In the illustrated embodiment the filter housing 11 has a total lengthof about 130 mm and a diameter of about 93 mm. The thickness of themicro-filter insert 21 is about 13.5 mm, the diameter of themicro-filter element 22 is about 62 mm, the diameter of the normalfilter element 30 is about 55 mm, and the diameter of the central volume6A is about 35 mm. The diameter of the orifice 15 is about 3.0 mm, andthe ratio of total inlet area (the holes 10 in the inlet plate 9) to theorifice 15 is about 1:400. The length of the first micro-filter element21 is about 110 mm, the length of the second micro-filter element 22 isabout 45 mm, and length of the conventional oil filter element 30 isalso about 45 mm. In alternate embodiments, the dimensions could be moreor less. The above described embodiment is merely exemplary.

In one embodiment the fluid communication path comprises an orificeproviding passage for filtered oil into the open inner volume of thefirst oil filter element; the orifice having a flow path area that issmaller than a flow path area of said second oil inlet. In oneembodiment a ratio of the area of the second oil inlet to the area ofsaid orifice is about 400:1 or greater.

The foregoing and other dimensions, materials, pressures and the likeare exemplary, and are not to be construed as being a limitation uponthe practice of this invention.

In further embodiments of this invention it can be appreciated that theoverall length of the filter housing 11 could be reduced by a factor ofabout two by eliminating the second micro-fine filter element 22, and bymaking the length of the first micro-fine filter element 21 and the tube12 about equal to the length of the normal filter element 30. Thisembodiment of the HOFA is depicted in a simplified form in FIG. 2B.

Referring now to FIG. 13, an alternate embodiment of the filter assemblyis shown. In this embodiment, the filter assembly 50 generally comprisesa housing 52, the first filter element 30, the second filter elementcomprising the first and second filter members 21, 22, and a fluttervalve 54. The housing 52 is identical to the housing in the firstembodiment shown in FIG. 2 with the exception of the tube 12. The tube56, which replaces the tube 12, has a general tubular shape andsurrounds the first filter element 30 and the second member 22 of thesecond filter element. The tube 56 comprises an inwardly extending rim58 formed by a fold in the tube 56. The rim 58 forms two oppositesurfaces which the flutter valve 54 and an outlet plate 68 at the exitfrom the second flow path are positioned against.

Referring also to FIG. 14, a top plan view of the flutter valve 54 isshown. The flutter valve 54 is preferably comprised of Silicon or otherflexible material, such as rubber for example, and is resilientlydeflectable. The flutter valve 54 generally comprises a center section60, an enlarged thickness outer portion 62, and a downwardly extendingrim 64. The center section 60 comprises holes 66 therethrough. In theembodiment shown, the center section 60 comprises four holes 66.However, in alternate embodiments, the center section 60 could comprisemore or less than the four holes. In addition, the holes could bearranged in any suitable array. However, in a preferred embodiment, theholes 66 are offset from the center of the flutter valve 54.

Similar to the plate 19 in the embodiment shown in FIG. 2, the filterassembly 50 comprises the plate 68 located at the bottom of the secondmember 22 of the second filter element. The plate 68 is supported on oneside of the rim 58. The plate 68 comprises holes 70 which passed throughthe plate.

The first filter element 30 is provided as a unitary member with asupporting frame 72. The filter element 30 and supporting frame 72 cancomprise a conventional subassembly as known in the art. The top of thesupporting frame 72 comprises a recessed section which extends towardsthe void 6A in the open area 35. The top of the supporting frame 72 issubstantially closed except for a center aperture 15. In the embodimentshown, the holes 66 of the flutter valve 54 are offset or not alignedwith the center aperture 15. The holes 66 of the flutter valve 54 arealso offset or not aligned with the holes 70 in the plate 68.

The outer portion 62 of the flutter valve 54 forms a seal between thetop of the supporting frame 72 and the rim 58 of the tube 56. The rim 64of the flutter valve 54 also extends down along the side of thesupporting frame 72 and forms a seal therewith.

FIG. 13 shows the flutter valve at a home position. In the home positionthe center section 60 is spaced from the bottom surface of the plate 68and is spaced from the recessed section of the top of the supportingframe 72 having the outlet orifice 15. The flutter valve 54 ismaintained at this home position when there is no fluid pressuredifferential on opposite top and bottom sides of the flutter valve. Thisoccurs when the engine is at rest, or when the engine is at a steadystate of operation.

Referring also to FIGS. 15 and 16, the flutter valve is shown at twoother positions. In the position shown in FIG. 15, the flutter valve 54has its center section 60 moved to an up position. In this up position,the top surface of the center section 60 contacts the bottom surface ofthe plate 68. Because the holes 66 in the center section 60 are notaligned with the holes 70 in the plate 68, the holes 66 become blockedby the plate 68. Thus, oil is prevented from flowing through the holes66.

The position of the flutter valve 54 shown in FIG. 15 occurs when theengine is initially started and, during periods of engine acceleration.More specifically, when there is an increase in oil pressure at theholes 32, such as when starting the engine or during engineacceleration, oil pressure will increase in the open space 35 fasterthan oil pressure will increase at the outlet from the second filterelement proximate the holes 70. This is because there is a timedifference or time differential between the transmission of theincreased pressure through the second filter element 21, 22 verses thetransmission of the increased pressure through the first filter element30. Because the holes 66 are offset from the orifice 15, the flow of oilupward through orifice 15 initially presses against a portion of thecenter section 60 which does not have the holes 66. Thus, this initialforce moves the center section upward faster than if one of the holes 66was located directly above the orifice 15.

The second filter element 21, 22, because of its finer filteringcapability (smaller pore size), is slower to transmit the increased oilpressure therethrough. This time differential between pressuretransmission through the two filters 21,22 and 30, causes a pressuredifferential between the open space 35 and the exit from the secondmember 22 of the second filter element at holes 70. Thus, oil flows fromthe open space 35 through the orifice 15 in an upward direction towardsthe flutter valve 54.

Because the center section 60 of the flutter valve 54 is deflectable, asthe oil passes through the orifice 15 it presses against the center ofthe center section 60 and pushes the center section 60 upward againstthe plate 68. This causes the holes 66 to be closed by the plate 68 andsubstantially prevents the oil from flowing through the holes 70 andinto the second member 22 of the second filter element in a reversedirection. In other words, the flutter valve 54 functions as a checkvalve to prevent a flow of oil through the holes 70 in a reversedirection. Thus, the second filter element is substantially preventedfrom receiving oil which has been filtered by the first filter element30 directly from the open space 35. This allows a greater percentage ofoil to be filtered by the second filter element 21, 22 entering theholes 32 than would otherwise be provided if the flutter valve was notpresent.

When the oil pressure on opposite sides of the plate 68 approachesequalization, the center section 60 of the flutter valve 54 can returnback to its home position shown in FIG. 13. This return is due to theflutter valve's own internal resiliency. Oil filtered by the secondfilter element 21, 22 can now flow through the holes 70, through theholes 66, and out the orifice 15 to be mixed with oil filtered by thefirst filter element 30 in the open space 35.

FIG. 16 shows the center section 60 of the flutter valve 54 in a downposition. In this down position the bottom surface of the center section60 is located against the top surface 74 of the recessed section of thesupporting frame 72. Because the holes 66 in the center section 60 arenot aligned with the hole 15 in the supporting frame 72, the holes 66become blocked by the plate top surface 74. Thus, oil is prevented fromflowing through the holes 66 and hole 15.

The position of the flutter valve 54 shown in FIG. 16 occurs is duringperiods of engine deceleration. More specifically, when there is adecrease in oil pressure at the holes 32, oil pressure will decrease inthe open space 35 faster than oil pressure will decrease at the outletfrom the second filter element proximate the holes 70. This is becausethere is a time differential between the transmission of the decreasedpressure through the second filter element 21, 22 verses thetransmission of the decreased pressure through the first filter element30. The second filter element 21, 22, because of its finer filteringcapability, is slower to transmit the decreased oil pressuretherethrough. This causes a pressure differential between the open space35 and the exit from the second member 22 of the second filter element.Thus, oil flows through holes 70 faster that oil flows out of the openspace 35.

Because the center section 60 of the flutter valve 54 is deflectable, asthe oil passes through the holes 70 it presses against the centersection 60 and pushes the center section 60 downward against the topsurface 74. This causes the holes 66 to be closed by the top surface 74and prevents the oil from flowing through the hole 15 and into the openarea 35. In other words, the flutter valve 54 functions as a speedcontrol valve or pressure differential control valve to prevent a flowof oil through the holes 70 too fast. Thus, the second filter element issubstantially prevented from decreasing the pressure of oil in thesecond filter element too fast. This allows slower pressure fluctuationsin the second filter element than would otherwise be provided if theflutter valve was not present and, faster resumption of filtering by thesecond filter element after the engine accelerates again or obtains asteady state. The first filter element 30 is always working duringoperation of the engine regardless of whether or not a path through thesecond filter element 21, 22 is open or closed by the flutter valve.

When the oil pressure on opposite sides of the center section 60 of theflutter valve 54 approaches equalization, the center section 60 of theflutter valve 54 can return back to its home position shown in FIG. 13.This return is due to the flutter valve's own internal resiliency. Oilfiltered by the second filter element 21, 22 can now flow through theholes 70, through the holes 66, and out the orifice 15 to be mixed withoil filtered by the first filter element 30 in the open space 35. In analternate embodiment, the supporting frame 72 could have more than oneorifice 15 and, one or more of the orifice(s) could be aligned with oneor more of the holes 66, such as when the holes 66 are smaller than theorifice(s).

Referring now also to FIG. 17, another alternate embodiment of thepresent invention is shown. The filter assembly 80 has a smaller heightthan the filter assembly 50 shown in FIG. 13. The filter assembly 80does not comprise the second member 22 of the second filter element. Inaddition, the first filter element 82 has a smaller height then thefirst member 21 of the second filter element shown in FIG. 13.

In this embodiment, the filter assembly 80 generally comprises the firstfilter element 30 the supporting frame 72, a second filter element 82and a housing 84. The housing 84 includes a tube 86 which surrounds thefirst filter element 30 and the supporting frame 72. A top of the tube86 comprises a lip 90. The flutter valve 54 is sandwiched between thetop of the supporting frame 72 and the bottom surface of the lip 90. Thehousing 84 includes a member 92. The housing member 92 comprises a platesection 93 and a spacer section 95. The plate section 93 comprises holes94 through the housing member. The holes 94 allow oil to pass throughthe top of the second filter element 82 into a space 96 and through theholes 94 towards the top side of the flutter valve 54.

The flutter valve 54 for the embodiment shown engine FIG. 17 functionsin the same way as the flutter valve described with reference to FIGS.13-16. The housing member 92 is the same as the housing member 92 usedin the embodiment shown in FIG. 13. In addition, the first filterelement 30 and supporting frame 72 are the same as those used in theembodiment shown in FIG. 13. Thus, the alternate embodiment of FIG. 17illustrates that components, such as the housing member 92, first filterelement 30, and supporting frame 72, can be used in differentembodiments.

In accordance with one aspect of the present invention, a hybrid oilfilter assembly is provided comprising a housing forming a first oilflow path and a second oil flow path; a first oil filter element 30 forfiltering particles having a first minimum size, the first oil filterelement being located in the first oil flow path; and a second oilfilter element 21, 22 that surrounds the first oil filter element 30along a portion of the length thereof, the second oil filter element 21,22 being located in the second oil flow path for filtering particleshaving a second minimum particle size that is smaller than the firstminimum particle size. Oil in the first oil flow path that has beenfiltered by the first oil filter element 30 and oil in the second oilflow path that has been filtered by the second oil filter element 21,22, but not filtered by the first filter 30, first begin to mix togetherwithin a void 6A contained within the first oil filter element 30 beforebeing discharged from the hybrid oil filter assembly.

In accordance with another aspect of the invention, a liquid filterassembly is provided comprising a first liquid filter element 30; asecond liquid filter element 21,22; and a housing having the first andsecond liquid filter elements therein, and a plate 23 located along atop side of the second filter element and proximate a top of thehousing, the plate having holes 24 therethrough; a threaded motorengaging assembly connected to a bottom of the housing. The housing andfilter elements form a plurality of partially separate liquid flow pathsor path segments through a filter. The first filter element 30 islocated in a first one of the flow paths. The second filter element 21,22 is located in a second one of the flow paths. A portion 21 of thesecond filter element surrounds a portion of the first filter element30. The second filter element 21, 22 comprises a top side surface alonga bottom side of the plate 23 which forms a filtered liquid exit fromthe portion 21 of the second filter element through the holes in theplate.

In accordance with another aspect of the invention, a liquid filterassembly is provided comprising a first liquid filter element 30; asecond liquid filter element 21, 22; and a housing having the first andsecond liquid filter elements therein. The housing and filter elementsform at least partially separate liquid flow paths. The first filterelement is located in a first one of the flow paths. The second filterelement is located in a second one of the flow paths. At least a portion21 of second filter element surrounds at least a portion of the firstfilter element 30. The first and second liquid flow paths begin to mergein an open space 35 at a center of the first liquid filter element 30.

In accordance with another aspect of the invention, a liquid filterassembly is provided comprising a first liquid filter element 30 adaptedto filter particles larger than a first size; a second different liquidfilter element 21, 22 adapted to filter particles larger than a secondsize, the second size being smaller than the first size; and a housinghaving the first and second liquid filter elements therein, the housingforming a first liquid flow path having the first liquid filter elementtherein, and a second liquid flow path having the second liquid filterelement therein. The first and second liquid flow paths share a commoninlet pressure of liquid entering into the housing. Liquid from anoutlet of the first liquid flow path and liquid from an outlet of thesecond liquid flow path combine at a mixing area 35, wherein the filterassembly comprises a liquid flow path restriction orifice 15 proximatethe outlet of the second liquid flow path such that liquid pressure atthe orifice 15 proximate the outlet of the second liquid flow path islarger relative to liquid pressure at the outlet of the first liquidflow path into the mixing area 35. The first and second liquid flowpaths begin to merge in the open 35 space in a center of the firstfilter element 30.

Referring now to FIG. 18 a cut-away side view of a filter assembly 100is shown. The filter assembly 100 is preferably a vehicle oil filter.However, features of the invention could be used in other embodiments.The filter assembly 100 generally comprises a housing 102 and two filterelements 104, 106. The housing 102 is substantially similar toconventional vehicle oil filters with a base plate 108 adapted to bescrewed onto a fitting of a motor, a valve 110 at the base plate, and aexterior cover 112 attached to the base plate 108 and enclosing the twofilter elements 104, 106.

The housing 102 is substantially the same as a conventional oil filter,such as a NAPA or MOBIL oil filter. The first filter element 104 issubstantially the same as the filter elements used in conventional oilfilters, but is slightly shorter in height to fit with the othercomponents of the filter assembly inside the height of the exteriorcover 112. However, in alternate embodiments, the exterior cover couldhave any suitable height and the first filter element could be comprisedof any suitable filter material. Referring also to FIGS. 19 and 20, in apreferred embodiment the first filter element 104 is a conventionalpleated paper or fiberous composite having a general ring shape which isadapted to filter particles above about 40-10 microns in size. Incomingoil can flow from an inlet in the base plate 108 into an area 114between the exterior cover 112 and the outer perimeter side of the firstfilter element 104 to enter the first filter element and exit the firstfilter element into a central cavity 116 of the ring shape and out acentral bottom outlet of the base plate 108.

The filter assembly includes a cover plate 118, a flutter valve member120 and the second filter element 106 located on top of the first filterelement 104. Referring also to FIGS. 21-23, the cover plate 118comprises a hole 122, and top and bottom receiving areas 124, 126. Thebottom receiving area 126 is adapted to receive the top of the firstfilter element 104 as seen in FIG. 19. The flutter valve member 120 iscomprised of resilient flexible rubber or polymer material and, itscenter section is adapted to move up and down similar to the valvedescribed in FIG. 13-16 based upon fluid pressure variations. Theflutter valve member 120 has four holes 66. However, any suitablenumber, shape and size of holes could be provided. The flutter valvemember 120 functions substantially the same as the flutter valve 54described above. The hole 122 can be opened and closed as the fluttervalve member 120 moves up and down. Likewise, the holes 66 in theflutter valve member can be closed as the valve moves up and down.

The flutter valve member 120 is sized and shaped to be received in thetop receiving area 124 and comprises an enlarged outer rim 128 whichfunctions as an O-ring seal when the second filter element 104 pressesagainst the rim 128 when assembled with the housing 102. Thus, theflutter valve member comprises an integral O-ring seal. The outerperimeter of the cover member 118 is spaced from the interior side ofthe cover 112 to allow fluid to flow up into the area 134 above thesecond filter element 106.

The bottom of the second filter element 106 is inserted into the topreceiving area 124 of the cover plate 118. The second filter element 106is preferably comprised of a molded or formed porous plastic or polymermaterial. Molded or formed porous plastic or polymer filter members havebeen used in the medical industry, such as Mupor™ porous PTFE sold byPorex Corporation of Fairburn, Ga. Mupor™ porous PTFE can have a passsize as small as 5 micron or less for example, and can have a thicknessas small as only 2 mm or less for example. In alternate embodiments thethickness of the second filter element 106 could be any suitablethickness (more or less than 2 mm) and could comprise a varyingthickness at different locations. Porex Corporation also manufacturesporous plastic members made of other polymer materials, such as PE, PP,PDVF, EVA, NYLON 6, TPU, and SCP. Any suitable polyamide could be usedto form a porous plastic member.

The second filter element 106 preferably has a pass size or pore size ofabout 4-5 microns. A filter element with a pore size of about 1-2microns could be used, but would need to be very large and, thus, maynot be suitable for a smaller size embodiment such as a vehicle oilfilter package. Because the second filter element 106 is comprised of amolded or formed porous plastic or polymer material it can be used as astructural member to press against the top side of the flutter valvemember 120 at the rim 128 to thereby seal the junction of the secondfilter element with the cover member at the rim and prevent inadvertentbypass of fluid at the junction without going through the second filterelement. The nature of providing the second filter element with moldedporous plastic material allows the second filter element to be smallerthan otherwise available and have a smaller pore size than wouldotherwise be available with a paper or fiberous composite filterelement. Because the second filter element can also be used in astructural manner, an extra member, such as the outlet plate 68 shown inthe embodiment of FIG. 15 need not be provided.

Referring now also to FIGS. 24-27 an embodiment of the second filterelement is shown. In alternate embodiments, the second filter elementcould comprise any suitable size or shape. The second filter element 106generally comprises a wave shaped cross section as seen best in FIGS. 19and 26, but with stiffening ribs 130 as seen in FIGS. 20, 24 and 27. Thewave shaped cross section provides an increase surface area for thefluid to pass through the second filter element 106. Upper sides of thewave shape are adapted to be contacted by the exterior cover 112 of thehousing and pressed inward towards the cover plate 118. The upper sidesof the wave shape also comprise channels 132 to allow fluid to flowbetween the top sides of the wave shapes and the interior side of theexterior cover 112.

With the invention there is no need to provide an additional separatespring to bias the first filter element towards the base plate. Thecover 112 and subassembly 118, 120 and 106 can provide this biasingaction. About 5%-10% of the fluid flowing through the filter assemblywill flow through the micro filter 106 and about 95%-90% of the fluidwill flow through the first filter element 104. In tests of motor oilflow through a micro filter 68 mm round and 2 mm thick with a 10 micronpore size, the following test results were achieved for oil at 800 F. toobtain 100 ml of flow:

Pressure (approximate) Time (approximate) 15 psi 6 minutes 20 psi 4.5minutes 35 psi 55 seconds 60 psi 25 seconds

With a 5 micron pore size, at 45 psi, about 12 liters per hour can passthrough the micro filter.

In an alternate embodiment the flutter valve member might not beprovided. With the invention there is more tolerance during assemblythan would otherwise be available unless a separate spring was added. Aseparate spring would increase the cost of the filter assembly andincrease the height of the filter assembly. In an alternate embodiment,the second filter element could comprise two or more members or sectionhaving different pore sizes, such as one section having a pore size of 6microns and another section having a pore size of 4 microns. In analternate embodiment one or more of the sections could have pore sizesgreater or less than 4-6 microns. The one or more of the sections couldbe molded or overmolded with another one of the sections, or could bemerely connected to each other. The sections or layers could becomprised of different polymer materials. The invention could also beused in a hydraulic system filter and is not limited to a vehicle oilfilter.

Referring now to FIG. 28, a partial cross sectional view of an alternateembodiment of the invention is shown. The filter assembly 140 ispreferably a vehicle oil filter. However, features of the inventioncould be used in other embodiments. The filter assembly 140 generallycomprises a housing 102 and two filter elements 104, 142. The housing102 is substantially similar to conventional vehicle oil filters with abase plate adapted to be screwed onto a fitting of a motor, a valve atthe base plate, and a exterior cover 112 attached to the base plate andenclosing the two filter elements 104, 142.

The housing 102 is substantially the same as a conventional oil filter,such as a NAPA or MOBIL oil filter. The first filter element 104 issubstantially the same as the filter elements used in conventional oilfilters, but is slightly shorter in height to fit with the othercomponents of the filter assembly inside the height of the exteriorcover 112. However, in alternate embodiments, the exterior cover couldhave any suitable height and the first filter element could be comprisedof any suitable filter material. Referring also to FIG. 29, which showsthe filter assembly with the exterior cover 112 and a spring 146removed, in a preferred embodiment the first filter element 104 is aconventional pleated paper or fiberous composite having a general ringshape which is adapted to filter particles above about 40-10 microns insize. Incoming oil can flow from an inlet in the base plate 108 into anarea 114 between the exterior cover 112 and the outer perimeter side ofthe first filter element 104 to enter the first filter element and exitthe first filter element into a central cavity 116 of the ring shape andout a central bottom outlet of the base plate 108.

The filter assembly includes a cover plate 118, a flutter valve member120, the second filter element 142, a support plate 144, and a spring146, which are generally located above the first filter element 104.Referring also to FIGS. 30-33, the support plate 144 comprises holes150. The bottom receiving area 126 of the cover member 118 is adapted toreceive the top of the first filter element 104 as seen in FIG. 28. Theflutter valve member 120 is comprised of resilient flexible rubber orpolymer material and, its center section is adapted to move up and downsimilar to the valve described in FIG. 13-16 based upon fluid pressurevariations. The flutter valve member 120 has holes 66. The flutter valvemember 120 functions substantially the same as the flutter valve 54described above. The hole 122 in the cover member 118 can be opened andclosed by the flutter valve member 120 as the flutter valve member 120moves up and down. Likewise, the holes 66 in the flutter valve membercan be closed as the valve moves up and down by the cover member 118 andthe plate 144.

The flutter valve member 120 is sized and shaped to be received in thetop receiving area 124 of the cover member 118 and comprises an enlargedouter rim 128 which functions as an O-ring seal when the support plate144 presses against the rim 128 when assembled with the housing 102.Thus, the flutter valve member comprises an integral O-ring seal. Theouter perimeter of the cover member 118 is spaced from the interior sideof the cover 112 to allow fluid to flow up into the area 134 above thesecond filter element 142.

As seen in FIG. 30, the support plate 144 has the holes 150. The supportplate 144 is located above the flutter valve member 120. Oil can flowthrough the holes 150 from the second filter element 142 (from the area134) into the area above the flutter valve member 120 (unless the holes150 are closed by the flutter valve member 120.

The second filter element 142 is inserted into the top receiving area124 of the cover plate 118 above the support plate 144. The secondfilter element 142 is preferably comprised of a molded or formed porousplastic or polymer material. Molded or formed porous plastic or polymerfilter members have been used in the medical industry, such as Mupor™porous PTFE sold by Porex Corporation of Fairburn, Ga. Mupor™ porousPTFE can have a 5 micron pass size and can have a thickness of only 2mm. In alternate embodiments the thickness of the second filter element106 could be any suitable thickness (more or less than 2 mm) and couldcomprise a varying thickness at different locations. Porex Corporationalso manufactures porous plastic members made of other polymermaterials, such as Polyvinylidene Fluoride (PVDF), PE, PP, PDVF, EVA,NYLON 6, TPU, and SCP. Any suitable polyamide could be used to form aporous plastic member. The second filter element 142 could comprise anextruded member cut to height or a molded member for example.

As seen in FIG. 31, the second filter element in this embodiment has ageneral disk shape. The second filter element can be easily cut orstamped from a flat sheet of material. The material used to form thesecond filter element does not need a rigid shape because of the supportstructure for the second filter element. The second filter element 142preferably has a pass size or pore size of about 4-5 microns. A filterelement with a pore size of about 1-2 microns could be used, but wouldneed to be very large and, thus, may not be suitable for a smaller sizeembodiment such as in FIG. 28. The nature of providing the second filterelement with molded porous plastic material allows the second filterelement to be smaller than otherwise available and have a smaller poresize than would otherwise be available with a paper or fiberouscomposite filter element.

The spring 146 is used to provide a biasing action from the top of thecover 112. The spring could be comprised of any suitable material, suchas bronze, steel or high temperature plastic for example. The spring 146is able to press the components 144, 142, 128, 118 and 104 in a downwarddirection towards the base plate 108. As seen in FIGS. 32 and 33, inthis embodiment the spring 146 comprises a one-piece member with aperimeter section 152 and spring leafs 154. The leafs 154 extend inwardfrom the perimeter section 152 in a general cantilever fashion. Tops ofthe leafs 154 can press against the inside surface of the top of thecover 112. The perimeter section 152 can press the second filter element142 against the support plate 144. The material of the second filterelement can be slightly soft. Pressing of the seal against the top ofthe second filter element at its perimeter can form a seal at theperimeter of the second filter element with the support plate. This typeof spring can occupy minimal vertical height, and can nonethelessprovide a range taking capability. More specifically, the spring 146allows variations in the height of the other components 104, 118, 120,144, 142 and automatically adjusts. This can accommodate differentheight components for different models of filters or manufacturingtolerances. In alternate embodiments, any suitable type of spring(s)could be used.

Referring now to FIGS. 34-38 another alternate embodiment of theinvention will be described. In this embodiment the filter assembly 160generally comprises a housing 102, a first filter element 104, a secondfilter element 164, a flutter valve member 120, a support plate 144 anda spring 146. The flutter valve member 120, support plate 144 and spring146 are arranged the same as that shown in FIG. 28, but the perimetersection of the spring is located directly on the support plate 144. Theassembly 160 does not comprise the cover member 118. The structuralfeatures provided by the cover member 118 are, instead, provided by thesecond filter element 164 as further described below. The housing 102includes the base plate 108 and the exterior cover 112. An inlet valveis located at the base plate 108.

As seen in FIG. 36, the first filter element 104 sits on the base plate108. The first filter element is the same as that described above withreference to the other embodiments. The second filter element 164 has ageneral cup shape. More specifically, the second filter element 164comprises side walls 166 having a general tube shape and a cup bottomsection 168 substantially closing one end of the second filter element.As seen best in FIGS. 37 and 38. The cup bottom section 168 has a shapesubstantially the same as the cover member 118. More particularly, thecup bottom section 168 has a hole 122 and two receiving sections 124,126. However, in alternate embodiments any suitable shape(s) could beprovided for the second filter element. The side walls 166 also comprisegrooves 170 and 172 on the inside and outside surfaces. The grooves 170,172 can extend any suitable height(s) of the side walls 166, or mightnot be provided. The side walls 166 and cup bottom section 168 form aninterior container area 174.

The second filter element 164 is preferably comprised of a molded orformed porous plastic or polymer material. However, it could be cut froma block of material. Molded or formed porous plastic or polymer filtermembers have been used in the medical industry, such as Mupor™ porousPolytetrafluoroethylene (PTFE) sold by Porex Corporation of Fairburn,Ga. Mupor™ porous PTFE can have a 5 micron pass size and can have athickness of only 2 mm. In alternate embodiments the thickness of thesecond filter element 106 could be any suitable thickness (more or lessthan 2 mm) and could comprise a varying thickness at differentlocations. Porex Corporation also manufactures porous plastic membersmade of other polymer material(s), perhaps mixed with other material(s),such as for example Polyvinylidene Fluoride (PVDF), PE, PP, PDVF, EVA,NYLON 6, TPU, SCP, polyphenylene sulfide resin, polyolefin,thermoplastic binder powder, PPS, glass fibers, micro-spheres, roundcarbon filter activated carbon material, ABS, ABS/PC, Acetals, CA, CP,CAB, LCP, Nylons (PA), PBT, PEEK, PEI, PC, PPO, TPE and TPU. Anysuitable polyamide could be used to form a porous plastic member.

In this embodiment, the second filter element 164 is comprised of amolded porous plastic or polymer material, such as PTFE or PVDF forexample, with a 1-2 micron pass size. However, in alternate embodimentsthe material could have a larger or smaller pass size. The second filterelement 164 has a general invented cup shape. The second filter element164 is mounted over the first filter element 104. The end 176 of thesecond filter element 164 is attached to the base plate 108, such aswith a sealant, epoxy or adhesive. The grooves 172 can provide a pathfor oil to enter the space 178 (see FIG. 39). Referring also to FIG. 39,incoming oil can flow from the inlet in the base plate 108 to the space178 between the inside surface of the side wall 166 and the exteriorsurface of the first filter element 104. The oil can than take one oftwo additional path sections until it gets to the open area inside thefirst filter element 104 and out the outlet through the base plate 108.The oil can travel through the first filter element 104 into the openarea as shown by arrow 180. The oil can also travel through the sidewall 166 of the second filter element 164 into a space 182 between theexterior surface of the side wall 166 and the interior side of the cover112 as shown by arrow 184. The oil in this second path 184 can travel upto the top open area 186 and through the holes of the support plate 144(when not blocked by the flutter valve 120) and through the hole 122 ina bottom of the general cup shape of the second filter element (when notblocked by the flutter valve 120) to enter the open area inside thefirst filter element 104 and remix with the oil that when through thefirst filter element and exit from the filter assembly. The grooves 170can provide the space 182 and still allow the cover 112 to contact thesecond filter element 164 for a firm secure assembly.

In this embodiment, the second filter element 164, because of its shapeand position, has a much larger surface area for oil to enter into thesecond filter element. Thus, a smaller pass size, such as 1 micron, 2microns or 3 microns for example, can be used in the material whichmakes the second filter element. The larger surface area allows greatercleaning of the oil using the second path 184. The grooves 170, 172 alsoincrease surface area. However, the grooves need not be provided. Theassembly can comprise a sealant, epoxy or adhesive 188 to seal thebottom surface 190 except at proximate the hole 122.

With this embodiment the second filter element 164 could have a largermicro pass size (such as 5 microns for example) and thereby provide alonger working life for the filter assembly than a small size secondfilter element which would clog sooner. Alternatively, the second filterelement could have a smaller micro pass size (such as 2 microns forexample) and thereby provide a cleaner filtered oil. Alternatively, oradditionally, the size of the hole 122 could be larger; the size of thesurface area of the second filter element and its pass size controllingthe rate of flow rather than the size of the hole 122. It may also bepossible to use the invention without the flutter valve.

Referring now to FIGS. 40-42, views of different oil filters 192, 194,196 and cut away sections of housings members 198, 200, 202 used inEuropean style cars which could be adapted to include features of theinvention. The designs include a screw on cap 204, 206, 208 (206 and 208which are shown with cut away sections) which are screwed into thehousing members 198, 200, 202 to capture the oil filters 192, 194, 196.The oil filters do not have their own outer cover. Instead, the housingmembers 198, 200, 202 and caps 204, 206, 208 function as the outercovers. With this type of embodiment, the caps and/or the housingmembers could be configured to removably receive the micro filterelement and provide a second path to the micro filter element.

Referring now also to FIG. 43 another alternate embodiment is shown. Inthis embodiment a filter assembly 300 is provided comprising a firstfilter element 302, a second different filter element 304, an exteriorhousing 112, a spring 308, and a seal 310. The first filter element 302is the same as the filter element 104, but could be different. Thesecond filter element 304 is the same as filter element 164 except thesecond filter element 304 does not comprise the hole 122. Space 178 isprovided between the outer perimeter of the first filter element 302 andthe inner side perimeter of the second filter element 304. Fluid, suchas oil, can flow into the first filter element 302 from the space 178 asindicated by arrow 180. Fluid can flow into the second filter element304 from the space 178 and into space 182 as indicated by arrow 184. Thefluid in space 182 can flow into top area 312, back through the secondfilter element 304 at the top section 314, and into open center space116 of the first filter element 302.

Unlike the embodiment shown in FIG. 39, in this embodiment the filterdoes not comprise a flutter valve or the plate 144. This is because thesecond filter element is substantially rigid. Instead, the spring 308biases the second filter element 304 downward away from the top of theexterior housing 112. Thus, the fluid passes through the second filterelement 304 twice at the two filtering locations 314, 316. Seal 310 canbe a preformed seal or can comprise a sealing adhesive material orsimilar material. The spring 308 is preferably comprised of moldedsilicon, but could be made of other material(s), such as metal forexample, or any other forming process.

With the embodiment shown in FIG. 43 the first filter element 302filters a majority of the flow of oil through the filter. The secondfilter element 304 only filters a small percentage of the oil flowthrough the filter. However, substantially the entire top surface of thesecond filter element can be used to filter the oil; the top surface ofthe second filter element occupying a majority of the cross sectionalarea of the filter assembly 300 (such as over 95 percent for example).The sides wall 316 also provides an increased surface area. Thus, theheight of the filter assembly can be the same as a conventional filterassembly or smaller. The present invention can be used withoutincreasing the height of a filter assembly as compared to conventionalfilter assemblies.

With the present invention a conventional filter element could be usedfor the first filter element 302. Thus, Society of Automotive Engineers(SAE) testing of the filter assembly 300 might not be needed again. Thisis because the first filter element 302 would function the same as aconventional filter in a conventional filter assembly even if the secondfilter element 304 became completely clogged. Thus, the first and secondfilter elements function independently from each other. The presentinvention could merely comprise adding the second new filter element 304and enlarging the housing accordingly. The invention can provide theadvantage of an inexpensive manufacture by using previously designedcomponents from conventional filters. Thus, the entire filter does notneed to be redesigned.

Referring also to FIG. 44 another alternate embodiment is shown. In thisembodiment the filter assembly 318 comprises three filter elements 320,322, 324. The first filter element 320 is the same as the filter element104, but could be different. The second filter element 322 is the sameas the filter element 21, but could be different. The third filterelement 324 is the same as the filter element 142, but could bedifferent. The third filter element 324 can filter particles having asmaller size that the second filter element 322. Fluid can flow throughthe second and third filter elements 322 and 324 in series. Thus, largerparticles can be filtered by the second filter element 322 before theyreach the third filter element 324.

Referring also to FIGS. 45-47 another alternate embodiment is shown. Inthis embodiment the filter assembly 326 comprises a housing 112, a firstfilter element 328, a second filter element 330, a holder 332 and aspring 334. The first filter element 328 is the same as the filterelement 104, but could be different. The second filter element 330 isthe same as the filter element 142, but could be different.

The holder 332 sits on top of the top side of the first filter element328 and is preferably sealed with the top side of the first filterelement by a sealant, such as epoxy for example. As seen best in FIGS.46 and 47, the holder 332 generally comprises a bottom receiving area336 which receives a top portion of the first filter element 328. Theholder also has a top receiving area 338 which receives a bottom portionof the second filter element 330. A top side 340 of the holder 332 hasspacer ribs 342 and a hole 344 extends between the top and bottomreceiving areas. The second filter element 330 sits in the top receivingarea 38 on top of the ribs 342. The spring 334 biases the components330, 332 and 328 together against a bottom section of the housing 112.

The spacer ribs 342 provide a path between the bottom of the secondfilter element 330 and the hole 344 for fluid to flow into the hole 344after the fluid exits from the second filter element 330. The holder ispreferably made of a plastic or polymer material such that fluid cannotflow through the holder except through the hole 344. As seen in FIG. 45,fluid can flow into space 346. A majority of this fluid flows throughthe first filter element 328, but a portion (such as about 2-5 percentfor example) flows up past the outside of the holder 332, down throughthe second filter element 330 and through the hole 334 to mix with thefluid from the first filter element at area 116.

Referring also to FIGS. 48-49, another alternate embodiment is shown. Inthis embodiment a filter assembly 348 is provided which comprises ahousing 112, a first filter element 350, a second filter element 352 anda spacer spring 354. The first filter element 350 is the same as thefilter element 104, but could be different. The second filter element352 is mounted directly on top of the top side of the first filterelement 350 with a sealing adhesive 356 or similar material(s). Thesecond filter element 352 is comprised of a molded polymer material thesame as the filter 106 except for the shape of the second filter element352. The second filter element 352 is preferably comprised of a moldedor formed porous plastic or polymer material, such as Mupor™ porous PTFEsold by Porex Corporation of Fairburn, Ga. Porex Corporation alsomanufactures porous plastic or polymer members made of other polymermaterials, such as PE, PP, PDVF, EVA, NYLON 6, TPU, and SCP. Anysuitable polyamide could be used to form a porous plastic member. Inthis embodiment, the second filter element 352 has an annular bottomreceiving area 358 which receives the top side of the first filterelement 350. A top side of the second filter element 352 has a centerportion 360 which extends upward. In alternate embodiments other shapescould be provided.

The spacer spring 354 is preferably comprises of a resilientlydeformable material, such as silicon or a polymer material. The spacerspring is preferably molded into the shape shown, but any suitablemanufacturing process could be used. The spacer spring 354 has a generalring shape. In this embodiment the spacer spring 354 comprises spacersections 362 and connecting sections 364. The spacer sections 362contact the top side of the second filter element 350 and the bottomside 366 of the top of the housing 112. Thus, the top of the housing iskept spaced from the top side of the second filter element 352. Thisembodiment allows for every fast assembly of the filter with a reducednumber of components.

Fluid can flow into annular space 346. A majority of this fluid flowsthrough the first filter element 350, but a portion (such as about 2-5percent for example) flows up past the outside of the second filterelement 352 into area 312, through the lateral side of the second filterelement and down through the top side of the second filter element 352to mix with the fluid from the first filter element at area 116.

Referring also to FIGS. 50-52, another alternate embodiment is shown. Inthis embodiment the filter assembly 368 comprises a housing 112, a firstfilter element 370, a second filter element 372, a holder 374 and aspacer spring 376. The first filter element 370 is the same as theelement 104, but could be different. The holder 374 is the same as theholder 332 shown in FIGS. 46-47, but could be different. The secondfilter element 372 has a general disk ring shape with a center aperture378. The second filter element 372 is preferably an extruded polymermember made of a material similar to the filter element 352, such asMupor™ porous PTFE sold by Porex Corporation of Fairburn, Ga. PorexCorporation also manufactures porous plastic or polymer members made ofother polymer materials, such as PE, PP, PDVF, EVA, NYLON 6, TPU, andSCP. Any suitable polyamide could be used to form a porous plasticmember. In alternate embodiments other shapes could be provided.However, by extruding the porous filter material in a column shape andcutting it to height as it is extruded, the cost of manufacture of thesecond filter element 372 can be greatly reduced.

The center aperture 378 forms a seat for the spacer spring 376. Thespacer spring 376 is preferably comprised of a slightly deformableplastic or polymer material or rubber for example. The spacer spring 376has a generally plug shape with a bottom facing surface 380 that sits ontop of the top surface of the second filter element 372. The top surface382 rests against the bottom surface 366 of the top section of thehousing 112. Thus, the spacer 376 functions to keep the top of thehousing 112 spaced from the top of the second filter element 372 toprovide the space 312. The second filter element 372, because it issubstantially rigid, keeps the bottom surface 384 of the spacer 376spaced from the hole 334.

Incoming fluid can flow into annular space 346. A majority of this fluidflows through the first filter element 370, but a portion (such as about2-5 percent for example) flows up past the outside of the second filterelement 372 into area 312, down through the second filter element 372,and through the hole 334 to mix with the fluid from the first filterelement at area 116.

Referring now to FIG. 53, another alternate embodiment will bedescribed. The housing is not shown merely for the sake of clarity. Inthis embodiment the filter assembly has a first filter element 402, asecond filter element 404 and an interior top plate 406. The firstfilter element 402 is the same as the first filter element 104, butcould be different. The second filter element 404 has a general tubeshape with an open top and bottom into the interior of the tube shape.Referring also to FIG. 54, the second filter element 404 comprises asheet 408 of filtering material which is bent or rolled into the tubeshape and then its ends 410, 412 are attached to each other.

The ends are preferably sealed with each other by a sealant or otherseal 416. The sheet 408 is not pleated, but it could be. Instead, thesheet 408 is preferably comprised of a porous polymer member, such asdescribed above, carbon with a Nylon binder for example.

The interior top plate 406 has outer holes 414 to allow fluid to passfrom the exterior side of the second filter element 404 to the top sideof the plate 406. The interior top plate 406 also has an inner hole 416to allow fluid to pass from the top of the plate into the interior ofthe first filter element 402. Fluid can initially enter a gap betweenthe two filter elements 402, 404 and pass through the two filterelements in opposite directions.

FIG. 55 shows another embodiment of a second filter element comprised ofa rolled sheet member. In this embodiment the sheet has been rolledaround itself in a spiral type of configuration to form the tube shapedsecond filter element 420. This type of design can remove the need toseal the ends of the sheet with each other with the coil shape beingtightly wound to form the seal.

Referring now also to FIG. 56 another embodiment is shown. The housingis not shown for the sake of clarity and the assembly would preferablycomprise a spring, such as the spring 146 for example. In thisembodiment the filter assembly 422 comprises a first filter element 424,a second filter element 426, a third filter element 428, a top holder430, a mesh screen 432, and a bottom seal 434. The first filter element402 is the same as the first filter element 104, but could be different.

The second filter element 404 has a general tube shape with an open topand bottom into the interior of the tube shape. The second filterelement is preferably comprised of a combined carbon fiber and polymermember, such as a molded or extruded member. The screen 432 surroundsthe second filter element 426. The screen 432 prevents particles whichmight flack off of the second filter element 426 from reaching the thirdfilter element 428. The seal 434 seals the bottom of the second filterelement 426. A seal (not shown) seals the top of the second filterelement 426 at the top holder 430.

The first filter element 424 is located insider the second filterelement 426 with its top sealed against the bottom side of the holder430. The holder 430 is the same as the holder 118. The third filterelement 428 comprises a flat disk, such as the filter element 142. In apreferred embodiment, the three filter elements 424, 426, 428 areadapted to filter different size particles such as 40-10 microns, 10-5microns, and 5-2 microns respectively for example. A disk shaped meshscreen (not shown) could also be provided between the third filterelement 428 and the holder 430 to prevent tiny pieces of the filter 428from entering the engine if they inadvertently break off of the thirdfilter element.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

1. A liquid filter assembly comprising: a first liquid filter elementadapted to filter particles larger than a first size; a second differentliquid filter element adapted to filter particles larger than a secondsize, the second size being smaller than the first size, where thesecond filter element comprises a polymer porous member, where thesecond filter element is a one-piece member with a substantially solid,rigid disk shape, and where the one-piece member has a general diskshape with a height substantially smaller than a width of the generaldisk shape; a holder having a bottom side located at a top side of thefirst filter element, wherein the holder has a portion located along aside height of a lateral outer side of the second liquid filter elementsuch that the second liquid filter element is retained in a seat of theholder; a housing having the first and second liquid filter elementstherein, the liquid filter assembly forming a first liquid flow pathhaving the first liquid filter element therein and a second liquid flowpath having the second liquid filter element therein, wherein the firstand second flow paths are at least partially separate; and a springlocated directly between the one-piece member and the housing, whereinthe spring directly biases the one-piece member directly against theholder.
 2. A liquid filter assembly as in claim 1 further comprising aflutter valve resilient flap sheet located on a top side of the holder,and a structural member located above the flutter valve resilient flapsheet and biased by the spring against at least a portion of a top sideof the flutter valve resilient flap sheet.
 3. A liquid filter assemblyas in claim 1 wherein the holder is a separate member from the secondfilter element, and wherein the second filter element is located at atop side of the holder.
 4. A liquid filter assembly as in claim 3further comprising a flutter valve resilient flap sheet located betweenthe second filter element and the holder.
 5. A liquid filter assembly asin claim 1 wherein the one-piece porous polymer member comprises amolded or die cast porous polymer member.
 6. A liquid filter assembly asin claim 1 wherein the one-piece porous polymer member comprises anone-piece extruded porous polymer member.
 7. A liquid filter assembly asin claim 1 wherein the one-piece porous polymer member comprises asubstantially flat disk shape.
 8. A liquid filter assembly as in claim 1wherein the one-piece porous polymer member comprisespolytetrafluoroethylene (PTFE).
 9. A liquid filter assembly as in claim1 wherein the one-piece porous polymer member comprises a pore size ofabout 5 microns or less.